To connect a past action to now, use have or has + the past participle of the verb. Many are easy (visited, finished, lived), but some you just learn: been, gone, seen, eaten, done.
have / has + the past participle
I have visited Senfarren twice.
They have lived here for years.
She has eaten sushi before. (not "has eat")
Try it: I ___ that film three times. (have seen / have see / have saw) Answer: have seen — After have, use the past participle: have seen. "See" is the base verb, and "saw" is the past you use alone (I saw it yesterday). With have, it becomes seen.
has for he, she, it
Use have with I, you, we, they. Change to has with he, she, it.
I have finished. / You have finished.
She has finished. / He has finished.
We have met them. / It has stopped raining.
Not "She have finished her homework." — say "She has finished her homework.". With he, she, it, use has, not have.
Try it: She ___ her homework already. (has finished / have finished / has finish) Answer: has finished — With she, use has (not have): she has finished. And after has, use the past participle finished, not the plain "finish".
The past participle (-ed and a few odd ones)
After have / has, use the past participle of the verb. For most verbs, just add -ed: work → worked, live → lived, play → played. A few common verbs are different and you learn them: be → been, go → gone, do → done, have → had, see → seen, make → made, know → known, eat → eaten.
I have worked here for a year. (work → worked)
She has lived in Haffenville since May. (live → lived)
We have known each other for years. (know → known)
He has been ill since Monday. (be → been)
Not "We have know each other since school." — say "We have known each other since school.". After have / has, use the past participle known, not the plain "know".
Try it: We have ___ each other for ten years. (know) (known / knowed / knew) Answer: known — The past participle of "know" is "known" (not "knowed" — it is one of the odd ones). "Knew" is the past form, but after have/has you need the past participle: have known.
haven't / hasn't
For the negative, use haven't or hasn't + the past participle. (haven't = have not, hasn't = has not.)
I haven't seen that film.
He hasn't finished yet.
We haven't been to Senfarren.
Try it: He ___ his lunch yet. (hasn't eaten / haven't eaten / hasn't ate) Answer: hasn't eaten — With he, the negative is hasn't (not haven't). And after it comes the past participle eaten, not "ate": he hasn't eaten.
Have you ever ...?
To ask, put Have or Has first. To ask about a life experience, add ever: Have you ever ...?
Have you ever eaten sushi?
Has she ever been to Senfarren?
Have they finished?
Try it: ___ you ever been to Senfarren? (Have / Do / Are) Answer: Have — To ask about a life experience, start with Have: Have you ever been? "Do you been" and "Are you been" are not real forms, this one uses Have + the past participle.
use it for a life experience
One big job of have / has + past participle is to talk about a life experience — something that happened in your life when you don't say the exact time. Common words: ever (in questions), never, before.
I have visited Senfarren. (some time in my life, I don't say when)
She has never eaten sushi.
Have you ever ridden a horse before?
Try it: You want to ask about your friend's whole life, not one special day. Which fits? (Have you ever been to Senfarren? / Did you go to Senfarren yesterday? / Are you going to Senfarren?) Answer: Have you ever been to Senfarren? — For a life experience with no exact time, use have + the past participle with ever: Have you ever been...? "Did you go... yesterday" asks about one clear day, and "Are you going" is about the future.
use it for something that just happened
A third job of have / has + past participle is something that finished a short time ago, when the result matters now. just and already are common here.
I have just finished my work. (so I'm free now)
She has already eaten. (so she isn't hungry now)
We have lost our keys. (so we can't get in now)
Try it: Which sentence shows something that finished a moment ago, with a result now? (I have just missed the bus. / I miss the bus every day. / I will miss the bus.) Answer: I have just missed the bus. — "Have just missed" means it finished a moment ago and matters now (so I have to wait). "Miss every day" is a habit, and "will miss" is the future.
just, already (before the past participle)
just = a moment ago, already = sooner than expected. Both go before the past participle, between have / has and the verb.
I have just finished.
She has already left.
We have already seen it.
Try it: Where does "already" go? Pick the right sentence. (She has already left. / She already left. / She already has left.) Answer: She has already left. — Already goes between has and the past participle: She has already left. "She already left" drops the has, and "She already has left" puts already before has.
yet (at the end)
yet = up to now. It goes at the end of negatives and questions.
Have you eaten yet?
They haven't arrived yet.
I haven't finished yet.
Try it: He's still at work. He ___. (hasn't finished yet / doesn't finished yet / yet hasn't finished) Answer: hasn't finished yet — In a negative, use hasn't + the past participle, with yet at the end: He hasn't finished yet. "Doesn't finished" mixes up the verbs, and "yet hasn't finished" puts yet at the front.